Complicated ventricular arrhythmia and hematologic myeloproliferative disorder in RIT1-associated Noonan syndrome: Expanding the phenotype and review of the literature

Background

Noonan syndrome is an autosomal dominant disorder secondary to RASopathies, which are caused by germ‐line mutations in genes encoding components of the RAS mitogen‐activated protein kinase pathway. RIT1 (OMIM *609591) was recently reported as a disease gene for Noonan syndrome.

Methods and Results

We present a patient with RIT1‐associated Noonan syndrome, who in addition to the congenital heart defect, had monocytosis, myeloproliferative disorder, and accelerated idioventricular rhythm that was associated with severe hemodynamic instability. Noonan syndrome was suspected given the severe pulmonary stenosis, persistent monocytosis, and “left‐shifted” complete blood counts without any evidence of an infectious process. Genetic testing revealed that the patient had a heterozygous c.221 C>G (pAla74Gly) mutation in the RIT1.

Conclusion

We report a case of neonatal Noonan syndrome associated with RIT1 mutation. The clinical suspicion for Noonan syndrome was based only on the congenital heart defect, persistent monocytosis, and myeloproliferative process as the child lacked all other hallmarks characteristics of Noonan syndrome. However, the patient had an unusually malignant ventricular dysrhythmia that lead to his demise. The case highlights the fact that despite its heterogeneous presentation, RIT1‐associated Noonan syndrome can be extremely severe with poor outcome.

Outcomes of hydrocephalus secondary to congenital toxoplasmosis

OBJECTIVE

Hydrocephalus occurs in children with congenital toxoplasmosis and can lead to severe disability. In these cases, the decision to intervene is often influenced by the expectation of neurological recovery. In this study, clinical responses to neurosurgical intervention in children with hydrocephalus secondary to congenital toxoplasmosis are characterized.

METHODS

Sixty-five participants with hydrocephalus due to congenital Toxoplasma gondii infection were evaluated as part of the National Collaborative Chicago-based Congenital Toxoplasmosis Study, and their neuroradiographic findings were reviewed. Clinical outcomes were scored on the basis of cognition and motor skills through the use of IQ scores and Gross Motor Function Classification System (GMFCS) level. Outcomes were then analyzed in relation to approach to management, anatomy of hydrocephalus, and time from diagnosis of hydrocephalus to surgical intervention.

RESULTS

There was considerable variation in the outcomes of patients whose hydrocephalus was treated in early life, ranging from normal cognitive and motor function to profound developmental delay and functional limitation. Of the 65 participants included in the study, IQ and GMFCS level were available for 46 (70.8%). IQ and motor score were highly correlated (r = -0.82, p < 0.001). There were people with differing patterns of hydrocephalus or thickness of cortical mantle on initial presentation who had favorable outcomes. Time to neurosurgical intervention data were available for 31 patients who underwent ventriculoperitoneal (VP) shunt placement. Delayed shunt placement beyond 25 days after diagnosis of hydrocephalus was associated with greater cognitive impairment (p = 0.02). Motor impairment also appeared to be associated with shunt placement beyond 25 days but the difference did not achieve statistical significance (p = 0.13). Among those with shunt placement within 25 days after diagnosis (n = 19), the mean GMFCS level was 1.9 ± 1.6 (range 1-5). Five (29.4%) of 17 of these patients were too disabled to participate in formal cognitive testing, after excluding 2 patients with visual difficulties or language barriers that precluded IQ testing. Of the patients who had VP shunt placement 25 or more days after diagnosis (n = 12), the mean GMFCS level was 2.7 ± 1.4 (range 1-4). Of these, 1 could not participate in IQ testing due to severe visual difficulties and 8 (72.7%) of the remaining 11 due to cognitive disability.

CONCLUSIONS

VP shunt placement in patients with hydrocephalus caused by congenital toxoplasmosis can contribute to favorable clinical outcomes, even in cases with severe hydrocephalus on neuroimaging. Shunt placement within 25 days of diagnosis was statistically associated with more favorable cognitive outcomes. Motor function appeared to follow the same pattern although it did not achieve statistical significance.

Clustering of Toxoplasma gondii Infections Within Families of Congenitally Infected Infants

BACKGROUND

Family clusters and epidemics of toxoplasmosis in North, Central, and South America led us to determine whether fathers of congenitally infected infants in the National Collaborative Chicago-Based Congenital Toxoplasmosis Study (NCCCTS) have a high incidence of Toxoplasma gondii infection.

METHODS

We analyzed serum samples collected from NCCCTS families between 1981 and 2013. Paternal serum samples were tested for T. gondii antibodies with immunoglobulin (Ig) G dye test and IgM enzyme-linked immunosorbent assay. Additional testing of paternal serum samples was performed with differential-agglutination and IgG avidity tests when T. gondii IgG and IgM results were positive and serum samples were collected by the 1-year visit of the congenitally infected child. Prevalence of paternal seropositivity and incidence of recent infection were calculated. We analyzed whether certain demographics, maternal parasite serotype, risk factors, or maternal/infant clinical manifestations were associated with paternal T. gondii infection status.

RESULTS

Serologic testing revealed a high prevalence (29 of 81; 36%) of T. gondii infection in fathers, relative to the average seropositivity rate of 9.8% for boys and men aged 12-49 years in the United States between 1994 and 2004 (P < .001). Moreover, there was a higher-than-expected incidence of recent infections among fathers with serum samples collected by the 1-year visit of their child (6 of 45; 13%; P < .001). No demographic patterns or clinical manifestations in mothers or infants were associated with paternal infections, except for sandbox exposure.

CONCLUSIONS

The high prevalence of chronic and incidence of recent T. gondii infections in fathers of congenitally infected children indicates that T. gondii infections cluster within families in North America. When a recently infected person is identified, family clustering and community risk factors should be investigated for appropriate clinical management.

Patterns of Hydrocephalus Caused by Congenital Toxoplasma gondii Infection Associate With Parasite Genetics

Four anatomical patterns of hydrocephalus secondary to congenital Toxoplasma gondii infection were identified and characterized for infants enrolled in the National Collaborative Chicago-based Congenital Toxoplasmosis Study. Analysis of parasite serotype revealed that different anatomical patterns associate with Type-II vs Not-Exclusively Type-II strains (NE-II) (P = .035).

Prematurity and severity are associated with Toxoplasma gondii alleles (NCCCTS, 1981-2009)

BACKGROUND

Congenital toxoplasmosis is a severe, life-altering disease in the United States. A recently developed enzyme-linked immunosorbent assay (ELISA) distinguishes Toxoplasma gondii parasite types (II and not exclusively II [NE-II]) by detecting antibodies in human sera that recognize allelic peptide motifs of distinct parasite types.

METHODS

ELISA determined parasite serotype for 193 congenitally infected infants and their mothers in the National Collaborative Chicago-based Congenital Toxoplasmosis Study (NCCCTS), 1981-2009. Associations of parasite serotype with demographics, manifestations at birth, and effects of treatment were determined.

RESULTS

Serotypes II and NE-II occurred in the United States with similar proportions during 3 decades. For persons diagnosed before or at birth and treated in infancy, and persons diagnosed after 1 year of age who missed treatment in infancy, proportions were similar (P = .91). NE-II serotype was more common in hot, humid regions (P = .02) but was also present in other regions. NE-II serotype was associated with rural residence (P < .01), lower socioeconomic status (P < .001), and Hispanic ethnicity (P < .001). Prematurity (P = .03) and severe disease at birth (P < .01) were associated with NE-II serotype. Treatment with lower and higher doses of pyrimethamine with sulfadizine improved outcomes relative to those outcomes of persons in the literature who did not receive such treatment.

CONCLUSIONS

Type II and NE-II parasites cause congenital toxoplasmosis in North America. NE-II serotype was more prevalent in certain demographics and associated with prematurity and severe disease at birth. Both type II and NE-II infections improved with treatment.

CLINICAL TRIALS REGISTRATION

NCT00004317.

Vaccine-associated "wild-type" measles

Measles is the most contagious of the childhood exanthems and is the leading cause of vaccine-preventable deaths in children, mostly in developing countries. The prodromal stage, consisting of high fever and the triad of cough, coryza, and conjunctivitis, is followed by a caudal progressing rash over a period of 2 to 3 days. With a worldwide vaccination program in place, mortality and morbidity have decreased substantially. Receipt of the live attenuated vaccine generally causes no or only mild side effects such as a low-grade fever and a subtle rash. We report a 1-year-old boy who, 10 days after vaccination, developed vaccine measles which was clinically indistinguishable from the natural disease. Vaccine virus was detected by polymerase chain reaction in the patient's nasopharyngeal secretions.

Risk factors for Toxoplasma gondii infection in mothers of infants with congenital toxoplasmosis: Implications for prenatal management and screening

OBJECTIVE

The purpose of this study was to determine whether demographic characteristics, history of exposure to recognized transmission vehicles, or illness that was compatible with acute toxoplasmosis during gestation identified most mothers of infants with congenital toxoplasmosis.

STUDY DESIGN

Mothers of 131 infants and children who were referred to a national study of treatment for congenital toxoplasmosis were characterized demographically and questioned concerning exposure to recognized risk factors or illness.

RESULTS

No broad demographic features identified populations that were at risk. Only 48% of mothers recognized epidemiologic risk factors (direct or indirect exposure to raw/undercooked meat or to cat excrement) or gestational illnesses that were compatible with acute acquired toxoplasmosis during pregnancy.

CONCLUSION

Maternal risk factors or compatible illnesses were recognized in retrospect by fewer than one half of North American mothers of infants with toxoplasmosis. Educational programs might have prevented acquisition of Toxoplasma gondii by those mothers who had clear exposure risks. However, only systematic serologic screening of all pregnant women at prenatal visits or of all newborn infants at birth would prevent or detect a higher proportion of these congenital infections.

Exploring effects of different pictorial stimuli on written expression

This study explored how the type of pictorial stimulus affects the quality of an individual's written expression. Cole, Muenz, Ouchi, Kaufman, and Kaufman in 1997 furnished initial evidence supporting Hooper, et al.'s 1994 theory. A pictorial stimulus different from that used by Cole, et al. was developed from Hooper, et al.'s specifications, i.e., pictorial stimuli should be photographs rather than line drawings, should have a clear protagonist and should present a novel problem-situation that can be solved in a stepwise manner and compared to a conventional line drawing stimulus (from PIAT-R Written Expression) in its ability to evoke writing samples. It was hypothesized that the "Hooper" stimulus would yield higher scores than an atheoretical stimulus on items assessing structure and cohesiveness of the story, but not on items that assess writing mechanics. Participants comprised 25 men and women aged 17 to 46 years. Results indicate that Hooper, et al.'s theory is more plausible than a conventional line-drawing stimulus.

Disability benefits: what is the Social Security Administration thinking?

This article briefly describes decision-making standards and procedures used by the Social Security Administration in adjudicating disability insurance benefits claims. Correlatively, the article addresses and dispels some of the myths surrounding various outcomes of disability claims. It also describes the role of the treating physician and how a treating physician who wants to help his or her patient obtain disability benefits should respond to Social Security's requests for medical records and written reports.

Eye manifestations of congenital toxoplasmosis

PURPOSE

To determine the natural history of treated and untreated congenital toxoplasmosis and impact of this infection on vision.

METHODS

In this prospective, longitudinal study, 76 newborns were treated with pyrimethamine and sulfadiazine for approximately one year, and 18 individuals not treated during their first year of life entered the study after age 1 year (historical patients).

RESULTS

Chorioretinal scars were the most common eye finding in all patients and were most common in the periphery (58% of treated and 82% of historical patients). Macular scars were present in 54% of the treated patients; 41% were bilateral. Macular scars were present in 76% of the historical patients; 23% were bilateral. Visual acuity in the presence of macular lesions ranged from 20/20 to 20/400. Of the patients followed up from the newborn period and treated, 29% had bilateral visual impairment, with visual acuity for the best eye of less than 20/40. Causes for this visual impairment in eyes with quiescent lesions included macular scars, dragging of the macula secondary to a peripheral lesion, retinal detachment, optic atrophy, cataract, amblyopia, and phthisis. There were recurrences in both treated (13%, 7/54) and previously untreated historical patients (44%, 8/18). The total, median, and range of years of follow-up during which recurrences were observed were, for treated patients, 189 years (total), five years (median) and three to ten years (range) and, for historical, untreated patients, 160 years (total), 11 years (median), and three to 24 years (range). New lesions occurred in previously normal retinas and also contiguous to older scars. Active lesions appeared to become quiescent within ten to 14 days after beginning pyrimethamine and sulfadiazine therapy.

CONCLUSION

Many children with congenital toxoplasmosis have substantial retinal damage at birth and consequent loss of vision. Nonetheless, vision may be remarkably good in the presence of large macular scars. Active lesions become quiescent with treatment.

Eye manifestations of congenital toxoplasmosis

PURPOSE

To determine the natural history of treated and untreated congenital toxoplasmosis and impact of this infection on vision.

METHODS

In this prospective, longitudinal study, 76 newborns were treated with pyrimethamine and sulfadiazine for approximately one year, and 18 individuals not treated during their first year of life entered the study after age 1 year (historical patients).

RESULTS

Chorioretinal scars were the most common eye finding in all patients and were most common in the periphery (58% of treated and 82% of historical patients). Macular scars were present in 54% of the treated patients; 41% were bilateral. Macular scars were present in 76% of the historical patients; 23% were bilateral. Visual acuity in the presence of macular lesions ranged from 20/20 to 20/400. Of the patients followed up from the newborn period and treated, 29% had bilateral visual impairment, with visual acuity for the best eye of less than 20/40. Causes for this visual impairment in eyes with quiescent lesions included macular scars, dragging of the macula secondary to a peripheral lesion, retinal detachment, optic atrophy, cataract, amblyopia, and phthisis. There were recurrences in both treated (13%, 7/54) and previously untreated historical patients (44%, 8/18). The total, median, and range of years of follow-up during which recurrences were observed were, for treated patients, 189 years (total), five years (median), and three to ten years (range) and, for historical, untreated patients, 160 years (total), 11 years (median), and three to 24 years (range). New lesions occurred in previously normal retinas and also contiguous to older scars. Active lesions appeared to become quiescent within ten to 14 days after beginning pyrimethamine and sulfadiazine therapy.

CONCLUSION

Many children with congenital toxoplasmosis have substantial retinal damage at birth and consequent loss of vision. Nonetheless, vision may be remarkably good in the presence of large macular scars. Active lesions become quiescent with treatment.

Resolution of intracranial calcifications in infants with treated congenital toxoplasmosis

PURPOSE

To determine the natural history of intracranial calcifications in infants with treated congenital toxoplasmosis.

MATERIALS AND METHODS

Between January 1982 and March 1994, cranial computed tomography was performed in 56 infants with treated congenital toxoplasmosis when they were newborns and approximately 1 year old. Locations and sizes of intracranial calcifications were noted.

RESULTS

Forty newborns had intracranial calcifications. By 1 year of age, calcifications diminished or resolved in 30 (75%) and remained stable in 10 (25%) of these treated infants. Ten (33%) of the 30 infants whose calcifications diminished versus seven (70%) of the 10 infants with stable calcifications received less intensive antimicrobial treatment than the other treated infants. In contrast, a small number of infants who were untreated or treated 1 month or less had intracranial calcifications that increased or remained stable during their 1st year of life.

CONCLUSION

Diminution or resolution of intracranial calcifications was an unexpected and remarkable finding in infants with treated, congenital toxoplasmosis, consonant with their improved neurologic functioning.

Neonatal group B streptococcal infections

Group B streptococci remain a leading cause of life-threatening neonatal infection worldwide. The current estimate of incidence in the United States is 1.8 cases per 1000 live births, with a case-fatality ratio of 10% to 20%. Advances in understanding of the pathogenesis of septic shock and meningitis are yielding new approaches to the treatment of these serious infections. Selective intrapartum chemoprophylaxis with ampicillin has been shown to be both effective and cost effective and is gaining more widespread acceptance as a preventive measure. Conjugate vaccines consisting of type-specific group B streptococci capsular polysaccharides coupled to tetanus toxoid or protein membrane antigens of group B streptococci have been shown to prevent neonatal infection in a mouse model of maternal immunization. Such vaccines are now in trials of safety and immunogenicity in humans.

Neurologic and developmental outcome in treated congenital toxoplasmosis

BACKGROUND

Earlier studies have shown that infants with untreated congenital toxoplasmosis and generalized or neurologic abnormalities at presentation almost uniformly develop mental retardation, seizures, and spasticity. Children with untreated subclinical disease at birth have developed seizures, significant cognitive and motor deficits, and diminution in cognitive function over time.

OBJECTIVE

To determine neurologic, cognitive, and motor outcomes for children with congenital toxoplasmosis who were treated for approximately 1 year with pyrimethamine and sulfadiazine.

DESIGN AND METHODS

Systematic, prospective, and longitudinal neurologic, cognitive, and motor evaluations were performed for 36 individuals with congenital toxoplasmosis. These infants were born between December 1981 and January 1991 and were treated with pyrimethamine and sulfadiazine for approximately 1 year beginning in the first months of life. Compliance with medications was documented. These individuals were evaluated in a standardized manner in a single center in the first months of life and at approximately 1, 3.5, 5, 7.5, and 10 years of age. Their cognitive function was compared with the cognitive function of a nearest-age, same-sex sibling when such siblings older than 3.5 years were available for study.

RESULTS

Signs of active central nervous system infection (eg, cerebrospinal fluid [CSF] pleiocytosis, hypoglycorrhachia, elevated CSF protein, and, in some instances, seizures and motor abnormalities) resolved during therapy. Six of the 36 children had perinatal seizures. Four had their anticonvulsant therapy discontinued successfully within the first months of life, and two additional children developed new seizures at 3 and 5 years of age. Tone and motor abnormalities resolved by 1 year of age in 12 of 20 infants who exhibited abnormalities of tone and motor function at their initial neonatal evaluation. By February 1992, 29 of the 36 children had been evaluated when they were 1 year old, and 23 (79%) had a mean +/- standard deviation Mental Developmental Index (MDI) of 102 +/- 22 (range, 59 to 140). Six (21%) had a measure of their cognitive function that was less than 50. Results of sequential IQ tests, performed at 1.5 year intervals or greater, did not differ significantly over time (P > .05). Seven children with MDIs greater than 50 were compared with sibling controls; they had scores of 87 +/- 11 (range, 68 to 97) and their siblings had scores of 112 +/- 15 (range, 85 to 132) (P = .008). Seventeen of 18 children without hydrocephalus and six of eight children with obstructive hydrocephalus responsive to shunting had normal or near-normal neurologic and developmental outcomes. Children with hydrocephalus ex vacuo present at birth, with high CSF protein, and with lack of response to shunting have done less well.

CONCLUSIONS

Neurologic and developmental outcomes were significantly better for most of these treated children than outcomes reported for untreated children or those treated for only 1 month (P < .001). Although the level of cognitive function for treated children was less than for their uninfected siblings (P < .008), there was no significant deterioration in neurologic and cognitive function of the treated children tested sequentially. These favorable treatment outcomes justify systematic identification and treatment of pregnant women with acute gestational Toxoplasma infection and young infants with congenital toxoplasmosis.

Progress in the prevention of hearing loss in infants

Two leading causes of hearing loss in infants and young children have been bacterial meningitis due to Haemophilus influenzae Type b (Hib) and congenital toxoplasmosis. In this two-part review, we describe the essential nature and incidence of these two diseases and how the availability of a Hib vaccine effective and safe with infants as young as 2 mo of age; the prospect of universal immunization against Hib disease; the introduction of cephalosporin antibiotic and corticosteroid treatment; and the use of early and prolonged antimicrobial therapy with children with congenital toxoplasmosis promises significant reduction, if not complete eradication, of hearing loss in infants and toddlers attributable to Hib bacterial meningitis and congenital toxoplasmosis. As a result, there may be up to a third fewer children under the age of five with severe hearing impairment annually in the United States.

Immunogenicity and safety of Haemophilus influenzae type b-tetanus protein conjugate vaccine alone or mixed with diphtheria-tetanus-pertussis vaccine in infants

Haemophilus capsular polysaccharide-tetanus toxoid conjugate (PRP-T) and diphtheria-tetanus-pertussis (DTP) vaccines were administered in a single syringe (group 1) or separate syringes (group 2) to 284 infants at 2, 4, and 6 months of age. Group 1 infants had a slightly greater incidence of local reactions. Systemic reactions were similar. The geometric mean titers of polyribosylribitol phosphate (PRP) serum antibody concentrations after the third dose of PRP-T vaccine were 4.8 and 4.3 micrograms/ml for groups 1 and 2, respectively. Antibody responses to DTP antigens were also similar. The immunogenicity and safety of the PRP-T and DTP vaccines are equivalent when the vaccines are administered in separate syringes or the same syringe to infants.

Early and longitudinal evaluations of treated infants and children and untreated historical patients with congenital toxoplasmosis: the Chicago Collaborative Treatment Trial

Between December 1981 and May 1991, 44 infants and children with congenital toxoplasmosis were referred to our study group. A uniform approach to evaluation and therapy was developed and is described herein along with the clinical characteristics of these infants and children. In addition, case histories that illustrate especially important clinical features or previously undescribed findings are presented. Factors that contributed to the more severe disabilities included delayed diagnosis and initiation of therapy; prolonged, concomitant neonatal hypoxia and hypoglycemia; profound visual impairment; and prolonged, uncorrected increased intracranial pressure with hydrocephalus and compression of the brain. Years after therapy was discontinued, three children developed new retinal lesions (without loss of visual acuity when therapy for Toxoplasma gondii was initiated promptly), and three children experienced a new onset of afebrile seizures. Most remarkable were the normal developmental, neurological, and ophthalmologic findings at the early follow-up evaluations of many--but not all--of the treated children despite severe manifestations, such as substantial systemic disease, hydrocephalus, microcephalus, multiple intracranial calcifications, and extensive macular destruction detected at birth. These favorable outcomes contrast markedly with outcomes reported previously for children with congenital toxoplasmosis who were untreated or treated for only 1 month.

Comparison of the safety and immunogenicity of acellular (BIKEN) and whole-cell pertussis vaccines in 15- to 20-month-old children

OBJECTIVE

To compare the immunogenicity and reactogenicity of a two-component acellular pertussis vaccine (BIKEN) with whole-cell diphtheria and tetanus toxoids and pertussis vaccine (WC-DTP) when administered to children aged 15 to 20 months.

DESIGN

A randomized, double-blind study.

SETTING

Children in this study were from 12 general pediatric practices (11 were private and one was university-affiliated) and one inner-city university pediatric clinic.

PARTICIPANTS

Two hundred forty-six children aged 15 to 20 months who had received a three-dose primary series of standard WC-DTP vaccine during infancy.

SELECTION PROCEDURES

Children were randomly assigned to receive either WC-DTP or one of three lots of acellular diphtheria and tetanus toxoids and pertussis vaccine (DT-aP) in a 1:3 ratio at the 11 private practices and in a 1:1 ratio at the university-affiliated practice and inner-city university pediatric clinic.

INTERVENTIONS

The DT-aP vaccines contained 23.4 micrograms each of pertussis toxin and filamentous hemagglutinin per 0.5 mL and the same concentrations of diphtheria and tetanus toxoids as WC-DTP. Serum samples were obtained on the day of immunization and 4 to 6 weeks later. Adverse reactions at 6, 24, 48, and 72 hours were recorded by parents who were contacted by telephone at 24 and 72 hours and 14 days after immunization.

MEASUREMENTS/MAIN RESULTS

An indirect enzyme-linked immunosorbent assay method was used to determine IgG antibody response to pertussis toxin and filamentous hemagglutinin and IgG, IgA, and IgM to tetanus toxoids; a Chinese hamster ovary cell assay was used to measure functional antibodies to pertussis toxin; serum neutralization on VERO cells assayed diphtheria anti-toxin. Recipients of the DT-aP vaccine had fewer local reactions in the first 6 to 48 hours and fewer systemic reactions at 24 hours than did recipients of the WC-DTP vaccine. Acetaminophen was administered to 31% of DT-aP recipients compared with 63% of WC-DTP recipients. Infants given DT-aP had higher geometric mean antibody titer levels against pertussis antigens after vaccination.

CONCLUSION

The BIKEN DT-aP vaccine used in this study is less reactogenic and more immunogenic for selected pertussis antigens than the WC-DTP vaccine in children aged 15 to 20 months.

Development of IgM antibody to group B Streptococcus type III in human infants

An ELISA was developed to measure IgM antibody to albumin-coupled native capsular polysaccharide of type III group B streptococcus (GBS). The assay was standardized by two double-label methods that agreed within 33%. In quantitative assays, the range of IgM antibody to type III GBS in the sera of 94 adult pregnant women was 1.2-50.6 micrograms/ml (median, 5.4), while each of 38 cord serum samples contained less than 0.03 micrograms/ml IgM antibody. Neonatal rats were passively immunized with a serially diluted human serum containing 15 micrograms/ml IgM and undetectable IgG antibody to type III GBS. The rats were protected against lethal infection with an IgM antibody concentration of 0.5 micrograms/ml. In single serum samples from 31 healthy infants less than 2 years old and serial specimens from 5 infants with type III GBS infections, specific IgM antibody was detectable by 3 months of age. Levels greater than or equal to 0.5 micrograms/ml were present in all samples from infants greater than 7 months of age. The acquisition of specific IgM antibody is inversely correlated with the age-limited incidence of type III GBS infections in young children.

Antimicrobial prophylaxis of neonatal group B streptococcal sepsis

This article reviews available studies on prevention of neonatal group B streptococcal infections with antimicrobial prophylaxis. The data show that short-term administration of ampicillin to parturients with prenatal streptococcal colonization and perinatal risk factors effectively prevents these serious infections. A strong case can be made for prenatal screening for group B streptococcal carriage to identify mothers whose babies are at risk.

Maternal screening in prevention of neonatal infections: current status and rationale for group B streptococcal screening

Maternal screening--either selective or universal--is an accepted component of a number of strategies for prevention of congenital and perinatal infections. Using the results of maternal screening at prenatal visits and the presence of perinatal risk factors during labour, neonatal group B streptococcal (GBS) early-onset disease can be prevented by selective intrapartum chemoprophylaxis. Possible variations on this strategy may employ semiquantitative tests for GBS colonization at prenatal visits or, possibly, rapid bacterial diagnosis intrapartum. Based on the incidence and economic impact of GBS disease, selective intrapartum chemoprophylaxis appears cost-effective in United States populations, but may not be so in countries with lower incidence rates.

Prevention of early-onset neonatal group B streptococcal disease with selective intrapartum chemoprophylaxis

Most cases of neonatal group B streptococcal disease with early onset have an intrapartum pathogenesis. Attack rates are increased substantially in infants born to mothers with prenatal group B streptococcal colonization and various perinatal risk factors (premature labor, prolonged membrane rupture, or intrapartum fever). In a randomized controlled trial, we studied the effect of selective intrapartum prophylaxis with ampicillin in 160 such high-risk women. In infants born to mothers who received intravenous ampicillin during labor, as compared with controls who received no treatment, neonatal colonization with group B streptococci was present in 8 of 85 (9 percent) versus 40 of 79 (51 percent; P less than 0.001), colonization at multiple (greater than or equal to 3) sites was observed in 3 of 85 (4 percent) versus 24 of 79 (30 percent; P less than 0.001), and bacteremia occurred in none of 85 versus 5 of 79 (6 percent; P = 0.024). The side effects of ampicillin were limited to a single episode of urticaria in a mother who had no history of penicillin allergy. We conclude that intrapartum ampicillin prophylaxis in women with positive prenatal cultures for group B streptococci who have certain perinatal risk factors can prevent early-onset neonatal group B streptococcal disease.

Human IgG antibody to group b Streptococcus type III: comparison of protective levels in a murine model with levels in infected human neonates

We determined the serum concentration of human IgG antibody to the native capsular polysaccharide of group B Streptococcus (GBS) type III needed to passively protect mice against lethal homologous challenge. Antibody was measured by an ELISA, standardized by two methods, and corrected for nonprecipitating antibody. A concentration of 1.3 micrograms of IgG antibody to GBS type III/ml protected 126 (97%) of 130 mice from an 80%-96% lethal dose bacterial challenge. Concentrations of IgG antibody to GBS type III in sera from 42 infected infants were less than or equal to 0.3 micrograms/ml. Concentrations of antibody ranged from less than 0.02 to 21.7 micrograms/ml in sera from 102 unselected pregnant women (median, 0.05 microgram/ml); 13% had concentrations greater than or equal to 1.3 microgram/ml. Levels in 25 women colonized with GBS type III who gave birth to normal infants were significantly higher and ranged from 0.1 to 10.7 microgram/ml (median, 0.78 micrograms/ml). In a study of transplacental passage of antibody, protective levels were found in a number of infants with gestational ages between 28 and 36 weeks.

Protective levels of human immunoglobulin G antibody to group B streptococcus type Ib

We studied the concentration of circulating human immunoglobulin G (IgG) antibody to the native capsular polysaccharide of group B streptococcus (GBS) type Ib necessary to protect mice against lethal challenge by laboratory and clinical GBS Ib strains. Antibody was measured by an enzyme-linked immunosorbent assay in which native polysaccharide antigen coupled to human serum albumin was used. The assay was standardized by a quantitative precipitation test, using native antigen and specific human IgG antibody purified by affinity chromatography. IgG anti-GBS Ib antibody level-protection curves for 90% lethal dose challenge of mice were sigmoidal. The curves of whole serum and affinity-chromatographed IgG anti-GBS Ib were superimposable. The serum concentrations of human antibody required for complete protection of mice varied with the infecting strain and ranged from 0.038 to 0.175 microgram/ml. Protective levels of human IgG anti-GBS Ib were lower than those we found previously for homologous protection against GBS Ia challenge (range, 0.25 to 1.0 microgram/ml).

Type-specific capsular antigen is associated with virulence in late-onset group B Streptococcal type III disease

Strain differences have been postulated to explain the observation that group B Streptococcus type III (GBS III) late-onset disease occurs in only a fraction of colonized infants. To determine the distribution of type-specific polysaccharide antigen (Ag) in GBS III, Ag was measured by rocket immunoelectrophoresis in both supernatant fluids and EDTA extracts and by radial immunodiffusion in multiple HCl extracts of the pellet from cultures of 10 strains of GBS III. Capsular Ag was defined as the sum of Ag in EDTA extracts + Ag in multiple HCl extracts. Both Ag in EDTA extracts and Ag in supernatant fluids correlated with capsular Ag (r = 0.94). GBS III strains were obtained from the blood of 19 infants with late-onset sepsis, from the cerebrospinal fluid or blood of 22 infants with late-onset meningitis, and from mucosal surfaces of both 18 infants and 12 mothers of infants with low levels of type-specific antibody and asymptomatic colonization. Mean values of Ag in supernatant fluids in strains from infants with late-onset sepsis (1.50 +/- 0.08 micrograms/ml) and late-onset meningitis (1.67 +/- 0.09 micrograms/ml) were significantly greater than those in asymptomatic colonization strains (1.14 +/- 0.05 micrograms/ml; P less than 0.001). The number of organisms required for a 50% lethal dose in the chick embryo, determined in 29 strains, was inversely related to Ag in supernatant fluids (r = -0.60). The demonstration that the quantity of capsular Ag produced by GBS III strains is related to their virulence in chick embryos and to their invasiveness in susceptible infants supports the hypothesis that Ag is a virulence factor in humans.

Selective intrapartum chemoprophylaxis of neonatal group B streptococcal early-onset disease. II. Predictive value of prenatal cultures

To determine the value of prenatal cultures in defining maternal colonization status at delivery, 5,586 pregnant women were screened at prenatal visits for vaginal and rectal carriage of group B streptococci (GBS). GBS were isolated from 1,272 (22.8%). At delivery, semiquantitative cultures were obtained from 393 prenatal carriers, of whom 264 (67.2%) retained carriage at delivery. Seventeen (8.5%) of 200 women with negative prenatal cultures acquired carriage. The predictive value of a positive prenatal culture was highest (72.5%) in women with prenatal vaginal and rectal colonization and lowest (59.7%) in women with only rectal colonization. The predictive value varied inversely with the interval between prenatal sampling and delivery. In mothers with prenatal carriage, density of colonization at parturition was not predicted by the sites of prenatal colonization. Density of colonization, however, strongly influenced rates of vertical transmission to neonates and rates of heavy infant colonization. Ten infants born to prenatally cultured mothers developed group B streptococcal early-onset disease; the mothers of eight (80%) of the 10 had prenatal colonization with the homologous GBS serotype.

Selective intrapartum chemoprophylaxis of neonatal group B streptococcal early-onset disease. III. Interruption of mother-to-infant transmission

The effect of intrapartum ampicillin treatment on vertical transmission of group B streptococci (GBS) was examined in 575 prenatally colonized parturient women and their 580 newborn infants. Eighty women (43 receiving ampicillin) with premature labor and/or prolonged rupture of amniotic membranes were randomized. The other 495 were stratified into groups of 358 (31 receiving ampicillin) with no perinatal risk factors; 119 (28 receiving ampicillin) with premature labor and/or prolonged membrane rupture; and 23 (18 receiving ampicillin) with intrapartum fever. Ampicillin virtually eliminated vertical transmission in the treatment group with no risk factors and in both treatment groups with premature labor and/or prolonged membrane rupture. GBS colonization of neonates was detected only in women with intrapartum fever or brief (less than 1 hr) duration of treatment prior to delivery. Ampicillin treatment was associated with a highly significant reduction in maternal postpartum vaginal colonization by GBS. There were six group B streptococcal early-onset infections in infants of untreated subjects and no cases in treated subjects.

Selective intrapartum chemoprophylaxis of neonatal group B streptococcal early-onset disease. I. Epidemiologic rationale

Between 1973 and 1981, 61 cases of neonatal group B streptococcal early-onset disease occurred among 32,384 infants born at Michael Reese Hospital and Medical Center, Chicago. Forty-one (67%) of the 61 affected infants were bacteremic at birth, implying intrapartum acquisition of infection. No significant deviations from the overall attack rate of 1.9 per 1,000 live births were associated with maternal demographic factors, but increased attack rates were associated with birth weights of less than or equal to 2.5 kg (7.9 per 1,000), rupture of amniotic membranes greater than 18 hr before birth (7.6 per 1,000), and intrapartum fever (6.5 per 1,000). Forty-five (74%) of the 61 affected infants and 15 (94%) of the 16 with fatal outcome had one or more of these three perinatal risk factors. Based on an intrapartum vaginal carriage rate of 16.7% among parturients with perinatal risk factors, an attack rate of 45.5 per 1,000 was estimated for infants born to colonized "high-risk" parturients, a subgroup comprising approximately 3% of our obstetric population. These findings provide a compelling epidemiologic rationale for trials of selective intrapartum chemoprophylaxis of neonatal group B streptococcal early-onset disease.

Estimation of the protective level of human IgG antibody to the type-specific polysaccharide of group B Streptococcus type Ia

Human IgG antibody to the type-specific polysaccharide antigen of group B Streptococcus type Ia in the sera of mice was measured by enzyme-linked immunosorbent assay, previously standardized by quantitative precipitation, 24 hr after passive immunization with human serum or affinity-chromatographed antibody. The concentrations of antibody needed to protect mice against 90% lethal dose challenge varied with the bacterial inoculum and ranged from 0.25 to 1 microgram/ml using five strains of group B Streptococcus type Ia. Affinity-chromatographed antibody gave results comparable to serum, indicating the specificity of the antibody and the absence of other humoral factors in protection with this serum. Sera from 11 infected infants and their mothers had concentrations of antibody of less than or equal to 0.17 micrograms/ml, below the protective level delineated in the experimental model. Twelve percent of 50 adult women and 36% of 25 women colonized with group B Streptococcus type Ia had antibody levels of greater than or equal to 1 microgram/ml.

Isolation guidelines for obstetric patients and newborn infants

Available isolation guidelines for use in hospitals have often overlooked the infectious diseases and unique interactions of obstetric patients and their newborn infants. To help fill this void, we present our hospital's isolation policies for obstetric and neonatal patients and guidelines for maternal-infant contact and breast-feeding. These policies represent a multidisciplinary consensus of opinion and available epidemiologic data and have been found useful and practical in a single large teaching hospital. Other institutions should be able to adapt these guidelines to their own patient populations, personnel, and physical facilities.

An enzyme-linked immunosorbent assay (ELISA) for human IgG antibody to the type Ia polysaccharide of group B streptococcus

An ELISA was developed to measure human IgG antibody to the native polysaccharide antigen of GBS serotype Ia. Because the polysaccharide binds poorly to polyvinyl chloride, its adherence was enhanced by activation with cyanogen bromide and coupling to HSA in a molar ratio of polysaccharide to albumin of 1:4.5. There was minimal loss of sialic acid during coupling, and the coupled antigen showed identity with uncoupled native antigen by Ouchterlony analysis. OD values obtained by ELISA showed a log-linear relation to concentration of specific antibody in whole and affinity-chromatographed human sera measured by quantitative precipitation over a range of 0.25 to 3.5 microgram/ml. In replicate ELISA experiments using serially diluted human serum, dilutions with antibody content as low as 0.016 microgram/ml could be reliably differentiated from PBS or agammaglobulinemic serum. The concentration of antibody in 98 selected human sera measured by ELISA correlated well (r = 0.89, p less than 0.001) with results obtained by indirect IF assay. This quantitative ELISA for GBS antibody is rapid, convenient, economical, and suitable for routine use.

Rapid identification of material colonization with group B streptococci by use of fluorescent antibody

To identify women colonized with group B streptococci during parturition, we used pooled type-specific fluorescent antibody to examine vaginal swabs enriched by preincubation in selective broth medium. In preliminary experiments, group B streptococcus strain III-Bell was reliably detectable with fluorescent antibody at concentrations of greater than 10(5) colony-forming units per ml, achieved after 6 h of incubation of small inocula (18 to 26 colony-forming units). Of the vaginal swabs from 924 parturient women examined prospectively by both fluorescent antibody and selective bacteriology techniques, group B streptococci were isolated in 154. The sensitivity of the fluorescent antibody technique increased with increasing incubation time and ranged from 49% (3 to 6 h) to 81% (7 to 12 h) to 83% (13 to 18 h) to 93% (greater than 18 h). Colonized mothers identified within 6 h by the fluorescent antibody technique had higher rates of vertical transmission to their newborn infants (61%) than colonized mothers whose fluorescent antibody examinations were negative within this time interval (32%; P = 0.027). However, because of the timing of their admissions, none of the colonized mothers of the four infants who developed early-onset group B streptococcal sepsis were identified with fluorescent antibody until after delivery. Although its sensitivity approaches selective culture methods after 6 h of incubation, fluorescent antibody examination of vaginal swabs does not appear to offer a practical approach to identifying colonized parturient women for intrapartum antibiotic prophylaxis of group B streptococcal infection.